Bicalutamide-Teva Drug Interactions

No pharmacodynamic or pharmacokinetic interactions have been demonstrated between bicalutamide and LHRH analogues.
In vitro studies suggest that R-bicalutamide acts as a CYP 3A4 inhibitor and has a weaker inhibitory effect on CYP 2C9, 2C19, and 2D6 activities.
Although clinical studies using antipyrine as a marker of CYP activity showed no evidence of an interaction potential with bicalutamide, mean midazolam exposure (AUC) was increased up to 80%, after co-administration of bicalutamide for 28 days. For substances with a narow therapeutic index, such an increase could be relevance.
Therefore, the concomitant administration of terfenadine, astemizole or cisapride is contraindicated and caution is required when concomitantly prescribing ciclosporin and calcium channel blockers. Dosage reduction may be required for these products, particularly if there is evidence of enhanced or adverse effect. For ciclosporin, it is recommended that plasmatic levels and clinical condition should be frequently and regularly monitored at the beginning and after stopping the administration of bicalutamide.
Caution is required during concomitant administration of substances that might inhibit oxidation of bicalutamide, i.e, medicinal products containing ketoconazole or cimetidine. This may be increase the plasmatic levels of bicalutamide and subsequently the adverse effects.
Studies in vitro suggest that bicalutamide can displace the coumarin anticoagulant warfarin from protein binding sites. Therefore, frequent and monitoring of prothrombin time is recommended after starting the administration of bicalutamide to patients who concomitantly use coumarin anticoagulants.